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A land plant‐specific thylakoid membrane protein contributes to photosystem II maintenance in A rabidopsis thaliana
Author(s) -
Liu Jun,
Last Robert L.
Publication year - 2015
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1111/tpj.12845
Subject(s) - thylakoid , photosystem ii , arabidopsis thaliana , biology , mutant , biophysics , microbiology and biotechnology , photoinhibition , photosystem , arabidopsis , chloroplast , photosynthesis , biochemistry , gene
Summary The structure and function of photosystem II ( PSII ) are highly susceptible to photo‐oxidative damage induced by high‐fluence or fluctuating light. However, many of the mechanistic details of how PSII homeostasis is maintained under photoinhibitory light remain to be determined. We describe an analysis of the Arabidopsis thaliana gene At5g07020, which encodes an unannotated integral thylakoid membrane protein. Loss of the protein causes altered PSII function under high‐irradiance light, and hence it is named ‘Maintenance of PSII under High light 1’ ( MPH 1). The MPH 1 protein co‐purifies with PSII core complexes and co‐immunoprecipitates core proteins. Consistent with a role in PSII structure, PSII complexes (supercomplexes, dimers and monomers) of the mph1 mutant are less stable in plants subjected to photoinhibitory light. Accumulation of PSII core proteins is compromised under these conditions in the presence of translational inhibitors. This is consistent with the hypothesis that the mutant has enhanced PSII protein damage rather than defective repair. These data are consistent with the distribution of the MPH 1 protein in grana and stroma thylakoids, and its interaction with PSII core complexes. Taken together, these results strongly suggest a role for MPH 1 in the protection and/or stabilization of PSII under high‐light stress in land plants.